The present invention relates to a photographing method and a photographing apparatus using a photo sensor having a photoconductive layer formed on an electrode and a liquid crystal polymer composite, where liquid crystal is dispersed and fixed in resin.
It is known that a liquid crystal polymer composite can be prepared by mixing liquid crystal with resin and by dissolving it in a common solvent, and after this solution is coated by a spinner, the solvent is evaporated and dried, and the liquid crystal phase and the resin phase are separated by phase separation. The liquid crystal polymer composite can also be prepared by dissolving liquid crystal and monomer or oligomer of UV-setting resin in a common solvent, and under the condition where the mixture of the liquid crystal and the monomer is dried at a temperature to form an isotropic phase, ultraviolet ray is irradiated to polymerize the monomer, and the resin phase and the liquid crystal phase are separated by phase separation.
In the phase separation of the liquid crystal phase and the resin phase, liquid crystal phase in spherical or other shape is dispersed in the resin in some cases, or resin balls are dispersed in the liquid crystal phase with a skin layer on the surface in some other cases.
Refractive index in the orienting direction of the liquid crystal phase is adjusted in such manner that it becomes approximately equal to the refractive index of the resin. Because the refractive index in the non-oriented status is different from the refractive index of the resin, light is scattered at interface between the liquid crystal phase and the resin under a non-oriented condition immediately after preparation of the liquid crystal medium, and transmittance of the medium is decreased. When electric field is applied on the liquid crystal medium and the liquid crystal is oriented in a direction perpendicular to the plane of the medium, scattering is eliminated, and the light is transmitted.
If smectic liquid crystal having memory property is used as the liquid crystal, even when electic field is applied to orient the liquid crystal and electric field is then removed, the oriented status is maintained. When it is heated to a temperature where the liquid crystal phase is turned to isotropic phase and is then cooled down, it can be restored to the non-oriented status.
To record an image information on the liquid crystal medium, a transparent electrode 22 and a liquid crystal polymer composite layer 23 are sequentially formed on a transparent support member 21 to prepare a liquid crystal recording medium 20, and a transparent electrode 12 and a photoconductive layer 13 are sequentially formed on a transparent support member 11 to prepare a photo sensor 10 as shown in FIG. 1. The liquid crystal recording medium 20 and the photo sensor 10 are placed at face-to-face position with an air gap between them. Then, voltage is applied from a power source 30 between the two electrodes, and image exposure is performed on the photo sensor 10. The electric field on the liquid crystal is changed according to intensity of the exposure. Liquid crystal is oriented according to the electric field, and an image information corresponding to the image exposure can be recorded.
There is another method to record an image on a liquid crystal recording medium using a photo sensor: As shown in FIG. 2(a), a transparent electrode 12, a photoconductive layer 13, a liquid crystal polymer composite layer 23, and an upper electrode 22 are sequentially formed on a transparent support member 11 to prepare an integrated type recording medium. Or, as shown in FIG. 2(b), a transparent electrode 12, a photoconductive layer 13, a dielectric intermediate layer 14, a liquid crystal polymer composite layer 23, and an upper electrode 22 are sequentially laminated to prepare an integrated type recording medium. Image exposure is performed with the photo sensor by the same procedure, and by applying voltage between the two electrodes from the power source 30, an image information can be recorded on the liquid crystal layer.
The image information recorded on the liquid crystal medium can be converted to electric signal by an image reading device as shown in FIG. 3. In FIG. 3, illumination light with adequate wavelength selected in an optical system comprising a light source 40, an IR cut filter 41, a band-pass filter 42, and an illumination lens 43 is irradiated to a liquid crystal recording medium 20. The light passing through in the liquid crystal medium is adjusted in such manner that an image is formed on a CCD line sensor 50 through an image forming lens 44. The liquid crystal recording medium is placed on a movable stage (not shown), and said stage is controlled by a stepping motor. By converting the transmitted light by a CCD sensor to electric signal as the stage is moved, the image information is read.
The image signal converted to electric signal is outputted to a CRT or a printer when necessary.
In case it is attempted to record an image by the exposure under voltage application as described above, satisfactory image may not be obtained unless the image is recorded under adequate voltage application. Also, because the characteristics of the image to be recorded are changed according to the application voltage, an image of the desired characteristics may not be recorded unless correlation between the application voltage and the characteristics of the image to be recorded are well identifed.
To solve the above problems, it is an object of the present invention to provide a photographing method and a photographing apparatus, by which it is possible to control the recording characteristics of an image to be recorded by changing voltage applying conditions and to record the image by setting the application voltage to match the desired characteristics of the image.
To attain the above object, the method for recording image information according to the present invention comprises a photo sensor having a photoconductive layer formed on a transparent electrode and a liquid crystal recording medium having a liquid crystal polymer composite layer consisting of resin and liquid crystal formed on an electrode, said photo sensor and said liquid crystal recording medium placed face-to-face with an air gap therebetween to form a separate type information recording medium, image exposure is performed to the photo sensor, said liquid crystal is oriented by applying voltage between the two electrodes, and image information is recorded, whereby an application voltage, at which initial distribution voltage to the liquid crystal medium determined by capacities of the liquid crystal medium and the photo sensor is 1/2 or less of threshold voltage of the liquid crystal medium, is defined as an upper limit application voltage, a sum V1 of saturation voltage of the liquid crystal medium and breakdown voltage, or an application voltage V2 where equilibrium potential of the liquid crystal medium obtained from resistance of the photo sensor based on base current of the photo sensor and from resistance of the liquid crystal medium is higher than the threshold voltage, whichever is higher, is defined as a lower limit application voltage, and an image is recorded by setting the application voltage between the upper limit application voltage and the lower limit application voltage.
The present invention is characterized in that image characteristics are controlled by changing the application voltage within the preset range.
Also, the apparatus for recording image information according to the present invention comprises a photo sensor having a photoconductive layer formed on a transparent electrode and a liquid crystal recording medium having a liquid crystal polymer composite layer consisting of resin and liquid crystal formed on an electrode, said photo sensor and said liquid crystal recording medium placed face-to-face with an air gap therebetween to form a separate type information recording medium, image exposure is performed to the photo sensor, said liquid crystal is oriented by applying voltage between the two electrodes, and image information is recorded, whereby there are provided means for measuring resistance of the liquid crystal medium, means for determining base current of the photo sensor, and control means for setting application voltage range, said control means calculates an upper limit application voltage, defined as the voltage, at which initial distribution voltage to the liquid crystal medium determined by capacities of the liquid crystal medium and the photo sensor is 1/2 or less of the threshold voltage of the liquid crystal medium, and also calculates a lower limit application voltage as a sum V1 of saturation voltage of the liquid crystal medium and breakdown voltage, or an application voltage V2 where equilibrium potential of the liquid crystal medium obtained from resistance of the photo sensor based on base current of the photo sensor and from resistance of the liquid crystal medium is higher than the threshold voltage, whichever is higher, and the application voltage is controlled within the range of said upper limit application voltage and said lower limit application voltage.
According to the present invention, the range of the external application voltage is set at least based on the resistance of the liquid crystal, threshold voltage of the liquid crystal medium, and base current of the photo sensor, and by changing the application voltage in accordance with the desired image characteristics within the preset range, photographing can be achieved with the desired image characteristics.
Further, it is preferable to provide a coating layer on the surface of the fired porous ceramic molded material.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.